I was watching the Suns the other day and thinking about Nash still playing at the highest level and he's only a few years from 40. I'm several years younger than Nash and I hurt for days after I play. I know he has trainers that work to keep him in shape but it still seems like paying with 20 year old's several days a week would have to wear on him

you have to train a lot, with all types of stuff, and eat lots of protein, especially at such an age.

If you're constantly working out, and your body is constantly rebuilding the muscles then you can get into a rhythm where you can avoid lots of soreness, especially if you take long showers/baths after the workouts, massage your muscles a bit, and keep them warm while you're resting.

The worst is when you only play once every one or two weeks, then you're gonna be sore after every time but you're never gonna build yourself up to a rhythm where your body is taking your activity seriously again, and that's the part that gets worse as you age (along with joints and injuries,) younger athletes can take days off from doing things like stretching, and working out in general, and it usually even benefits their performance because it allows them to fully recover, but the older you get the more you need to make sure you're constantly on the move, never on a "lazy streak."